The 3rd generation mobile communication standards include FDD (Frequency Division Duplex), TDD HCR (Time Division Duplex, High Chip Rate) and TDD LCR (Time Division Duplex, Low Chip Rate). WiMAX joined the 3rd generation mobile communication standards recently. Usually FDD is named WCDMA, and TDD LCR is named TD-SCDMA.
The core technology of TD-CDMA system focuses on Smart Antenna, Dynamic Channel Allocation, Unsymmetrical Allocation of the uplink/downlink service and the Joint detection receiving technology. TD-SCDMA network can be constructed in intra-frequency mode and is a code resource limited system, which overwhelms WCDMA system in frequency reusable efficiency.
The network configuration of TD-SCDMA can be implemented in the form of inter-frequency network or intra-frequency network. The latter further includes 1.6 MHz intra-frequency network and 5 MHz intra-frequency network. The multiple accessing for neighboring cells is based on FDMA for inter-frequency configuration. The assigned frequency resources can be utilized for all Node-Bs in 1.6 MHz intra-frequency network. The 1.6 MHz intra-frequency network configuration has the highest frequency efficiency with severe intra-frequency interference. 5 MHz intra-frequency configuration based on N frequency point protocol is the tradeoff of the inter-frequency and intra-frequency technology. In such a configuration, the 0th timeslot bearing common control information, such as PCCPCH/SCCPCH information, is inter-frequency configured, while the 1st to 6th timeslots are intra-frequency configured. Smart antenna and dynamic channel allocation can be adopted for intra-frequency configured TD-SCDMA system to decrease the strong intra-frequency interference.
FIG. 1 shows a typical TD-SCDMA network. As shown in FIG. 1, the TD-SCDMA network is a traditional 3G mobile communication network having a location area, a registration area, and a routing area concept. The TD-SCDMA network is also a mobile broadcast network with distributed transmission. The mobile user equipment (UE) does not care much for the downlink transmission from one special Node-B, but utilizes all downlink transmission from all recognizable Node-Bs by diversity combining. The effective channel estimation is shown in FIG. 2. The SFN and the communicating TD-SCDMA network can be merged into one layer in which some timeslots are used for traditional mobile communications and the other timeslots, for example, TS6, are reserved for mobile broadcast service.